Method and apparatus for improving utilization efficiency of wireless links for web-based applications

ABSTRACT

An improved data communication network including a wireless link for accessing, from an end user machine, objects in a selected web page retrievable from an Internet server by means of suitable request messages is described. The wireless link includes a subscriber unit coupled to the end user machine and a base station coupled to the server. Web page data packets retrieved from the server with the use of the request messages are intercepted and locally stored in a gateway unit on the base station side of the wireless link. The gateway unit generates, from the retrieved web page data packets, additional request messages suitable for retrieving, from the server, object data packets corresponding to the objects on the selected web page. Such retrieved object data packets are also stored in the gateway unit. At least a portion of the stored object data packets, together with the stored web page data packets, are selectively released for transmission in bundled form over a single assigned channel on the wireless link. Such transmitted object data packets are locally stored in an additional gateway unit on the subscriber unit side of the wireless link, while the transmitted web page data packets are forwarded to the end user machine. The end user machine re-generates the object retrieval request messages, which in turn are used to directly retrieve the object data packets locally stored in the additional gateway without the necessity of again traversing the wireless link.

RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.09/876,843, filed Jun. 6, 2001. The entire teachings of the aboveapplication(s) are incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to data communication networks including awireless link for transmitting data packets between an end user machineand a server, and more particularly to arrangements of this type foraccessing Internet content such as server-based web pages from the enduser machine.

An end user machine in such an arrangement utilizes a web browser torequest, retrieve and locally display web pages, each of which consistsof many objects of small size. The TCP protocol is typically used totransport this data over the wireless link between the end user machine(or client) and the Internet server to which the web page request isdirected. The wireless link includes a subscriber unit which is coupledto the end user machine, and a base station which is coupled to theserver and is in radio communication with the subscriber unit.

The use of the TCP protocol in such connections through a wirelessenvironment has several disadvantages. Such environment is especiallysubject to packet losses that are most often caused by signal loss andtemporary disconnects, resulting in missing or delayed acknowledgmentsignals between the end user machine and the server. TCP frequentlyinterprets such wireless packet loss as network congestion, even when nonetwork congestion is present. This is true whether packets are destinedfor the end user machine or the server. This increases the likelihoodthat the applicable TCP protocols at either end of the networkconnection will invoke congestion avoidance/slow start modes at theserver. In addition, each of the small objects on a retrieved web pagemust be transported over one or more separate TCP connections, whichseverely burdens the capacity allocation requirements on the wirelesslink. Consequently, the TCP connections never reach their optimumtransmission speeds, and the wireless network resources are veryinefficiently used.

These problems are especially acute in the case where an end usermachine is requesting access to web pages that are housed on an Internetserver. A separate connection from the client to the server has to beestablished through the wireless link not only when the client sends aweb page request but also when the client wants to retrieve theplurality of objects that typically are contained within the web page.Each of the requests for a web page and a separate object must beresponded to over the connection by the web server, and since typicallysmall amounts of data are involved each time in going across thewireless interface, an especially poor allocation of system resources ispresent.

SUMMARY OF THE INVENTION

These problems are significantly minimized with the use of a web cacheproxy gateway arrangement of the present invention, in which first andsecond proxy gateways are respectively associated with the subscriberunit and the base station on opposite sides of the wireless link. In anillustrative embodiment the first gateway establishes, with the end usermachine, a first TCP connection that replicates an end-to-end connectionbetween the end user machine and an Internet server housing a web pageto be retrieved. In like manner, the second gateway unit establishes,with the server, a second TCP connection that replicates a similarend-to-end connection. The separated proxy TCP termination points thuspresented by the gateways to the associated terminal machines allow theintervening wireless link itself to be separately optimized with awireless protocol without the necessity of transporting data in TCPformat through such link.

The second gateway makes a web page access request to the server onbehalf of the end user machine, and intercepts the resulting web pagedata packets from the server. The second gateway generates, from theintercepted web page data packets, request messages for all the objectscontained in the web page. The second gateway transmits such locallygenerated object requests to the server, and locally stores theretrieved object data messages. The locally stored web page messages,together with at least a portion of the locally stored object datamessages, are selectively transmitted to the first gateway in bundledform over the wireless link using a single connection.

The first gateway locally stores the selectively transmitted object datamessages, and forwards the web page data message to the end usermachine. The end user machine can then retrieves such locally storedobject data messages with the use of object data requests derived fromthe forwarded web page data message. This eliminates the necessity ofrepetitively assigning separate channels over the wireless link toretrieve each of such objects on the server side of the link.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

The invention is further illustrated in the following detaileddescription taken in conjunction with the appended drawing, in which:

FIG. 1 is a block diagram of a wireless data communication system havingfacilities for efficiently accessing server-based web pages from an enduser machine;

FIG. 2 is a block diagram of a wireless data communication system of thetype shown in FIG. 1 but incorporating the web cache proxy gatewayarrangement of the invention;

FIG. 3 is a block diagram of an embodiment of a web cache gateway of thepresent invention as incorporated on the subscriber unit side of thewireless link;

FIG. 4 is a more detailed block diagram of a portion of the gateway ofFIG. 3;

FIG. 5 is a block diagram of an embodiment of a web cache gateway of theinvention as incorporated on the base station side of the wireless link;and

FIG. 6 is a more detailed block diagram of a portion of the gateway ofFIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

A description of preferred embodiments of the invention follows. Whilethis invention has been particularly shown and described with referencesto preferred embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the scope of the invention encompassed by theappended claims.

Referring to FIG. 1, a conventional Internet server 11 is depicted forproviding content in the form of web pages which may be accessed by anend user machine 12 with the use of a conventional web browserapplication 13. Access to the server from the machine 12 is accomplishedthrough a data packet communication system 14. The system 14 includes awireless link 15 having at one end a subscriber unit 16, which typicallyincludes a wireless modem and associated components. The subscriber unitis coupled to the end user machine through a direct connection or via alocal area network 17, which may be a conventional Ethernet connection.The end user machine may be a laptop computer, a portable computer, apersonal digital assistant, or the like, which may be moved form placeto place.

The subscriber unit 16 is in radio communication with a base station 18on the server side of the wireless link 15. The base station 18 may beconventionally coupled to the server 11 through the Internet representedat 19.

The web pages housed on the server 11 are typically constructed inaccordance with HTML or similar protocols, and are accessed from the enduser machine 12 over the network 14 utilizing the web browser 13 togenerate the applicable HTTP web page request messages. Each web page istypically composed of many objects. The objects, in turn, are separatelyaccessed by means of separate HTTP object request messages generated bythe browser 13. Such objects may be represented, e.g., by hyperlinks onthe retrieved web page.

It has been generally necessary for the base station 18 to assign aseparate channel(s) over the link 15 to establish a connection by whichthe end user machine 12 can transmit each HTTP object request messageover the network 14 to the server 11, and retrieve object data packetsrepresenting the requested object. Each such separate connection, whichemploys a transport protocol such as TCP, is conventionally set up byutilizing suitable application software (not shown) associated with themachine 12 to generate TCP connection request packets bearing the IPdestination address of the server 11. Once a TCP connection isestablished, retrieval of a requested web page or one of its associatedobjects, as the case may be, may be carried out in a bi-directionalmanner using convention TCP protocols.

Successive bytes in the transmitted packets from the sending machine(the end user machine 12 or the server 11) will, in further accordancewith applicable TCP protocols, trigger successive acknowledgment signalsfrom the receiving machine at the other end of the established TCPconnection. The acknowledgment signals are transmitted to the sendingmachine over the same TCP connection. As is well known, use of the TCPprotocol for transmission over a wireless link leads to manyinefficiencies and loss of throughput because of TCP congestion controlmechanisms that are erroneously triggered when the protocol interpretsthe inevitable packet losses and delays on the wireless link ascongestion on the network. In addition, the necessity of constantlyassigning wireless channels for each of the many object and web pagerequests and responses necessary in a typical web browser session,together with the high overhead required when transmitting, over thewireless link, relatively large TCP headers in the packets representingsuch requests and responses, result in inefficient transfer of data andutilization of resources on the network.

In accordance with the invention, such problems are greatly reduced withthe use of the modified data communication system 14A illustrated inFIG. 2. A pair of web cache proxy gateways 26 and 27, to be described inmore detail below, are associated with the subscriber unit 16 and thebase station 18, respectively. In the arrangement shown, the gateway 26is represented as being incorporated in the subscriber unit 16, but suchgateway may also be a separate unit associated with, and located on thesame side of the wireless link 15 as, the subscriber unit 16. In likemanner, the gateway 27 is shown as an integral part of the base station18, but it may be alternately embodied as a separate unit associatedwith, and located on the same side of the wireless link 15 as, the basestation 18. A pair of conventional link-layer transceivers 28 and 29 arealso included in the subscriber unit 16 and the base station 18,respectively, and constitute the end points of the wireless link 15.

In order to establish a TCP session with a remote machine over thenetwork 14A, the end user machine 12 typically utilizes TCP connectionrequest packets bearing the IP destination address of such remotemachine. Such connection request packets are transmitted over the LANconnection 17 to the subscriber unit 16, where they are intercepted by aclient HTTP intercept module 31.

If the connection request packets detected by the module 31 bear the TCPport for HTTP traffic, together with an associated HTTP retrievalrequest that is illustratively destined to the Internet address of theserver 11, such retrieval request packets are directed to the gatewayunit 26 from the intercept module 31. Otherwise, the packets arediverted by the module 31 to the transceiver 28, where they are directedover the wireless link 15 and the transceiver 29 to their intendeddestination (not shown).

With respect to the HTTP retrieval request packets directed to it fromthe module 31, the gateway 26 is arranged to function as a local TCPend-point for the connection requested by the machine 12 in the mannerdescribed in applicant's copending application Ser. No. 09/850,531,filed May 7, 2001, entitled “Dual Split Proxy Gateway for ImprovingThroughput Performance Over a Wireless Interface”. (Such co-pendingapplication is assigned to the assignee of the present invention and isincorporated herein by reference.) In particular, the gateway 26associates the Internet IP address of the server 11 with such end pointto provide a replica of a direct TCP connection between the machine 12and the server 11. As a result, the gateway 26 act as a proxy for theserver 11, participating in standard TCP protocol exchanges with theend-user machine 12. This includes the generation of acknowledgmentmessages both for connection request messages and for subsequent datamessages originating at the machine 12. (It will be assumed that themonitor 31 is transparent to packets, including but not limited to suchacknowledgment messages, transmitted over such TCP connection in thedirection from the gateway 26 to the end user machine 12.)

As further set forth in the above-mentioned copending application, thegateway 26 includes facilities for converting the TCP format of theincoming connection request packets from the end user machine 12 to aselected wireless protocol format which may be separately optimized fortransmission over the wireless link 15. An illustrative embodiment ofsuch gateway 26 suitable for this purpose is represented in FIG. 3. Aproxy manager 32 is coupled to the output of the intercept module 31 toanalyze the associated connection information in the TCP headers of theincoming packets. The connection parameters analyzed by the proxymanager 32, which may include source and destination IP addresses andTCP port numbers of the server 11, are mapped with the aid of a sessiontable 33 into a short session identifier. Such information is forwardedfrom the proxy manager 32 to an HTTP session proxy unit 34 to associatethe data coming from the intercept module 31 with the converted datathat is to to exit the gateway 26 in wireless protocol format.

As shown in FIG. 4, the proxy unit 34 includes a TCP terminator 36 whichis assigned the IP address of the web server 11 by the proxy manager 32.The terminator 36 therefore acts as the proxy TCP end point, on behalfof the server 11, with respect to data arriving from the end usermachine 12 through the intercept module 31. The terminator unit 36removes the TCP framing from the intercepted connection request packets,and transfers the data from such packets (including the HTTP web pageretrieval requests), together with the session identifier informationfrom the proxy manager 32, to a wireless web protocol manager 37 (FIG.3). The manager 37 generates modified connection request packets inwhich the transferred data from each packet intercepted by the module 31is encapsulated with a header appropriate for the transmission over thewireless link 15 in a wireless protocol format selected by the manager37. Such wireless protocol header contains the above-mentioned sessionidentifier, the sequence number assigned to each such packet, and otherinformation that may be necessary to optimally format the packet inaccordance with the selected wireless protocol, which may illustrativelybe a link-layer protocol.

The gateway 26 (FIG. 2) forwards the modified connection request packetsto the transceiver 28, which transmits the modified packets over thewireless link 15 to the gateway 27 via the transceiver 29. In thegateway 27, a second wireless web protocol manager 41 (FIG. 5) extractsthe session identifier information from the wireless protocol headers ofthe incoming modified packets and forwards the modified packets to asecond HTTP session proxy unit 42.

A local TCP initiator 43 (FIG. 6) in the proxy unit 42 removes thewireless protocol headers from such packets. It also encapsulates thepacket data with TCP headers bearing the IP addresses of the end usermachine 12 and the server 11 as derived from the extracted sessionidentifier. This effectively reconstructs the original TCP connectionrequest message from the end user machine 12 (FIG. 2). The gateway 27 isassigned the IP address of the end user machine 12.

The initiator 43 (FIG. 6) forwards the reconstructed TCP connectionrequest packets over the Internet 19 (FIG. 2) to the server 11 toestablish a second TCP connection between the gateway 27 and the server.Since the initiator 43 presents the IP address of the end user machine12 to the server 11, the TCP connection just established between thegateway 27 and the server 11 will be a replica of an end-to-endconnection between the end user machine 12 and the server 11. Therefore,like the above-described first TCP connection established between themachine 12 and the gateway 26, the second TCP connection can engage inall standard TCP protocol exchanges as if there were such a directend-to-end connection between the server 11 and the machine 12. Suchexchanges include the generation, at the initiator 43, of acknowledgmentmessages that would be generated by the end user machine 12 (FIG. 2) inresponse to the transmission of data packets from the server 11.

Once the system 14A has been configured as just described to establish adual split proxy connection between the end user machine 12 and theserver 11, data packets can flow over such system in a bi-directionalmanner via the first and second TCP wired connections and theintervening wireless link layer.

When the server 11 receives the reconstructed HTTP web page requestmessage from the gateway 27 (as proxy for the end user machine 12) overthe second TCP connection, it generates HTTP web page data packetsrepresentative of the requested web page. Such web page data packets aretransmitted in TCP format over the Internet 19 to the gateway 27 througha server HTTP intercept module 51, which analyzes the incoming datastream. Any incoming packets that do not represent the web pagerequested by the end user machine 12 from the server 11 are diverted tothe link-layer transceiver 29 without going through the gateway unit 27in the base station 18. By contrast, the desired web page data packetsfrom the server 11 are routed from the intercept module 51 to the HTTPproxy unit 42 (FIG. 6) in the gateway 27.

In the proxy unit 42, the intercepted web page data message is locallystored in a cache 53 and is separately inspected by a scanner 54 forobjects contained in the web page. An object request generator 56coupled to the output of the scanner 54 creates, for all the objects onthe scanned web page, separate HTTP object retrieval messages which areapplied in sequence to the server 11 through the above-mentioned secondTCP connection via the intercept module 51 and the Internet 19 (FIG. 2).It will be assumed that, in a manner similar to that described above inconnection with the client HTTP intercept module 31, the module 51 istransparent to packets transmitted over the second TCP connection in thedirection from the gateway 27 to the server 11.

In response to each such object retrieval message, the server 11 returnsan HTTP object data message over the second TCP connection to the proxyunit 42 (FIG. 6). In further accordance with the invention, such objectdata messages from the retrieved web page are not immediatelytransmitted over the wireless link 15 but are instead locally stored inthe cache 53. The proxy unit 42 is provided with suitable facilities,represented as a cache release circuit 57, for selectively releasing atleast a portion of the locally stored object data messages (togetherwith the locally stored web page data message to which such objectsrelate) for transmission in bundled form over the wireless link asindicated in the next paragraph. Illustratively, the release circuit 57may be arranged to monitor the accumulation of packets in the cache(e.g., by tracking the accumulated object data against the correspondingobject retrieval request packets from the generator 56), and to directthe cache 53 to release, in bundled form, all the object data associatedwith the requested web page. Alternatively, the circuit 57 may bearranged to direct the release of the number of object data packetslocally stored during an interval selected by an adjustable timer (notshown) in the circuit 57.

Packets released from the cache 53 for transmission over the wirelesslink are first unencapsulated and applied, via the initiator 43, to theassociated protocol manager 41. The protocol manager appends a smallwireless protocol header to such unencapsulated data, and transmits thepackets as so converted to the gateway unit 26 (FIG. 2) in thesubscriber unit 16 through a path that includes the transceiver 29, anassigned traffic channel on the wireless link 15, and the transceiver28. (It will be understood that if not all of the released data can besent before such wireless traffic channel is reassigned, then additionaltransmissions will take place over channel(s) assigned in the futureuntil all of the data is sent.)

Because the locally stored object data messages representing a greatdeal of web data are transmitted at one time in bundled form over thewireless link, the necessity of continually assigning channel capacityfor separate transmissions of individual object and web page requestsand corresponding acknowledgment signals over such link is greatlyminimized.

When the transmitted object data packets from the gateway 27 arereceived by the first gateway 26 on the subscriber unit side of thewireless link 15, they are coupled through the protocol manager 37 (FIG.3) and locally stored in a cache 61 (FIG. 4) in the proxy unit 34.However, the web page data packets that were bundled with such objectdata packets are not stored. Instead, they are directly applied to theTCP terminator 36, which re-converts the web page data packets from theselected wireless protocol to the TCP protocol. The web page datapackets as so reconverted are then sent via the transparent interceptmodule 31 (FIG. 2) to the end-user machine 12 over the previouslyestablished first TCP connection.

Once such web page data packets are received by the end-user machine 12,the end-user machine can retrieve the associated object data packetsstored in the cache 61 (FIG. 4) in the HTTP session proxy 34. For thispurpose the end user machine, utilizing the browser 13, can scan the webpage represented by the received data packets to locally generate HTTPobject retrieval request messages identical to the object data retrievalmessages that were originally generated on the base station side of thewireless link. Release of the object data packets from the cache 61 maybe accomplished with the aid of a detector or other suitable releasecircuit 63 to which such locally generated object retrieval requestsignals are applied over the first TCP connection.

It will be appreciated that retrieval of the web data signals in themanner described above may be quickly and efficiently accomplishedwithout the necessity of repetitively requesting wireless resources(e.g. RF traffic channels) to transmit each individual object retrievalrequest message and object data response message through the wirelesslink 15.

Preferably, the cache release circuit 57 of FIG. 6 is provided withfacilities for preventing the packets locally stored in the cache 53from being unnecessarily transmitted over the wireless link from thegateway 27 to the gateway 26. This situation could occur, for example,when the subscriber utilizing the end user machine 12 (FIG. 2), afterrequesting a web page from the server 11, decides to terminate theapplicable TCP session, e.g., by transmitting a conventional TCP resetor abort signal over the first TCP connection before receipt of therequested data. When such reset signal arrives at the gateway 26 throughthe intercept module 31, the terminator 36 (FIG. 4) terminates the firstTCP connection, and the protocol manager 37 converts the reset signalinto a connection cancellation message in a format suitable fortransmission across the wireless link to the second gateway 27. Uponreceipt of such message the protocol manager 41 (FIG. 5) in the gateway27 reconstitutes the TCP reset signal, which is transmitted over thesecond TCP connection to the server 11 to terminate such connection in aconventional manner. The cancellation message is also applied to thecache release circuit 57 (FIG. 6), which instructs the cache 53 to“dump” its accumulated contents of web page and object data instead ofreleasing such data to the initiator 43 for format conversion andtransmission over the wireless link.

In the forgoing, the invention has been described, in part, inconnection with an exemplary embodiment thereof. Many variations andmodifications will now occur to those skilled in the art. For example,the first and second TCP connections in the system 14A (FIG. 2) may beset up from the server side of the system 14A, so that the first TCPconnection would extend between the server 11 and the gateway 27, andthe second TCP connection would extend between the gateway 26 and theend user machine 12. The mechanics of forming such reverse connectionswill mirror those described above, except that the end point of thefirst TCP connection as presented to the server 11 would be implementedby a second TCP terminator (not shown) in the gateway 27, while thestarting point of the second TCP connection as presented to the end usermachine 12 would be implemented by a TCP initiator (not shown) in thegateway 26. Also, it will now be evident that many of the advantages ofthe invention resulting from selectively transmitting web page objectmessages in bundled form over a single assigned channel on the wirelesslink may be achieved whether or not the system includes the double-splitTCP connection specified in the illustrative embodiment. It isaccordingly desired that the scope of the appended claims not be limitedto or by the specific disclosure herein contained.

1. In a data transmission system including a wireless link fortransmitting packets between an end user machine and a server thatstores content in the form of web pages containing objects, the wirelesslink comprising a mobile subscriber unit coupled to the end user machineand a base station coupled to the server and in radio communication withthe subscriber unit, a selected web page on the server being retrievedin the form of web page data packets in response to web page retrievalrequest packets, the objects on such web page being separatelyretrievable in the form of object data packets in response to objectretrieval request packets: A method for transmitting web pages over awireless link, comprising: intercepting web page data at a wireless basestation; locally generating at the base station, from the interceptedweb page data, object retrieval requests for objects within a selectedweb page; transmitting the locally generated object retrieval requeststo a web server to retrieve the corresponding objects; locally storing,at the base station site, the retrieved web page data and the retrievedobjects; and selectively transmitting the locally stored web page dataand at least a portion of the locally stored objects in bundled form toa subscriber unit connected to the wireless link.
 2. A method as definedin claim 1, in which the selectively transmitting step comprisestransmitting all of the locally stored objects.
 3. A method as definedin claim 1, in which the selectively transmitting step comprisestransmitting number of objects locally stored during a selected timeinterval.
 4. A method for transmission of a selected web page over awireless link, comprising: establishing between an end user machine anda subscriber unit a first TCP connection that replicates a TCPconnection between the end user machine and a web server; establishingbetween the base station and the web server a second TCP connection thatreplicates a TCP connection between the end user machine and the webserver; transmitting web page retrieval requests to the web server overa path including the first TCP connection, the wireless link and thesecond TCP connection to retrieve web page data representative of theselected web page; intercepting the retrieved web page data at the basestation; locally generating, from the intercepted retrieved web pagedata, object retrieval requests representative of objects associatedwith the selected web page; transmitting from the base station, thelocally generated object retrieval request packets to the web server toretrieve the corresponding objects; locally storing at the base station,the retrieved web page data and the retrieved objects; and selectivelytransmitting the stored web page data packets and at least a portion ofthe stored objects in bundled form to a subscriber unit of the wirelesslink.
 5. A method as in claim 4, further comprising: locally storing theobjects on the subscriber unit side of the wireless link for subsequentretrieval by the end user machine.
 6. A method as defined in claim 4, inwhich the transmitting step further comprises: forwarding the web pageretrieval requests over the first TCP connection and the second TCPconnection in TCP format, and forwarding such web page retrievalrequests over the wireless link in a selected wireless protocol format.7. A method as defined in claim 4, in which the first TCP connectionestablishing step further comprises: detecting at the subscriber unit,data transmitted from the end user machine, and setting up the first TCPconnection when the detected data comprises web page retrieval requestpackets.
 8. A method comprising the steps of: detecting, on a subscriberunit side of a wireless link, first retrieval request packetstransmitted from an end user machine; converting the detected firstretrieval request packets into third retrieval request packetsencapsulated in accordance with a selected wireless protocol;transmitting the third retrieval request packets over the wireless linkto a base station; re-converting the third retrieval request packetsback into first retrieval request packets at the base station;transmitting the re-converted first retrieval request packets to aserver to retrieve first data packets representative of a selected webpage; on the base station side, generating second retrieval requestpackets derived from the retrieved first data packets and correspondingto objects associated with the selected web page; transmitting thesecond retrieval request packets to the server to retrieve second objectdata packets representative of the corresponding objects on the selectedweb page; locally storing the retrieved first and second data packets;selectively releasing, in bundled form, the stored first data packetsand at least a portion of the stored second data packets; and convertingthe released first and second data packets to third and fourth datapackets, respectively, the third and fourth data packets beingencapsulated in accordance with the selected wireless protocol; andtransmitting the third and fourth data packets to the subscriber unitside of the wireless link.
 9. A method as defined in claim 8, furthercomprising the steps of: re-converting the third and fourth data packetsback into first and second data packets, respectively, on the subscriberunit side of the wireless link; locally storing the re-converted seconddata packets; and transmitting the re-converted first data packets tothe end user machine.
 10. A method as defined in claim 8, in which theselected wireless protocol is the native link-layer protocol of thewireless system.